The oropharyngeal microbiome of COPD patients and controls in a livestock dense area

Abstract

Livestock-related air pollution is a known respiratory health risk for patients with chronic obstructive pulmonary disease (COPD). It has been hypothesised that livestock-related air pollutants could affect respiratory health through modulation of the airway microbiome. Therefore we studied determinants of the oropharyngeal microbiota (OPM) composition of COPD patients and controls in a livestock-dense area.

Oropharyngeal swabs were collected from 99 (mostly mild) COPD cases and 184 controls (baseline), and after 6 and 12 weeks. Participants were non- or former smokers, and had not used antibiotics in the month before sampling. OPM composition was analysed using 16S rRNA-based sequencing in all baseline samples and 6 and 12 week samples of 20 randomly selected subjects (n=323 samples).

Preliminary analyses showed no significant differences in alpha- and beta-diversity metrics, and abundance of genera in univariable comparisons of cases and controls. The overall OPM composition differed by gender, current lung medication use, and season (univariable PERMANOVA, p<0.05). The annual average outdoor air pollutant levels (livestock emitted endotoxin and PM₁₀) at the home address was not related to overall OPM composition. Procrustes analysis showed moderate (0.52;0.66) correlation (p<0.05) between ordinations (Bray-Curtis dissimilarity NMDS) of 20 subjects analysed at 0, 6, and 12 weeks.

OPM profiles in COPD and controls were relatively stable over a 12-week period, indicating a single sample is quite representative for the individual OPM in COPD cases and healthy adults. Determinants of OPM composition included use of specific mediation. Multivariable analysis is needed to decipher independent drivers.